Bipolar affective disorder is a severe mental illness associated with low utilization of outpatient psychiatric services, and high rates of relapse and utilization of inpatient services; naturalistic studies indicate that about 50% of bipolar patients discharge from inpatient care are readmitted within 15-18 months. These data are particularly striking when viewed in the context of recent advances in the pharmacotherapy of bipolar disorder, demonstrating the urgent need for studies examining psychosocial influences on service use and outcome of bipolar patients, influences which have received scant attention to date. Family factors such as caregiver burden, social support and expressed emotion are known to exert a major influence on outcome in other major psychiatric disorders, but research on family factors in bipolar illness is virtually non-existent. The proposed research aims to examine the direct and indirect effects of family burden on outpatient service utilization, relapse and community tenure in bipolar illness, and to evaluate the scope of burden and associated mental health costs to families. 375 SADS-diagnosed bipolar patients consecutively admitted to an urban or suburban outpatient clinic and their family caregivers will be assessed on measures of patient symptoms and behavior, and on measures of family burden, health and coping: 1) upon admission; 2) 7 and 15 months later. Data on outpatient service utilization (duration, frequency, modality) will be entered into a computerized data base on an ongoing basis, and monthly measures of level and type of symptoms, role functioning and treatment compliance will be obtained. Linear structural equation analytic techniques (LISREL) will be used to model the relationships among exogenous (bipolar symptoms), mediating (family burden, health, coping) and service utilization and community tenure variables. Event history analysis will be employed to model the extent to which bipolar symptoms predict the risk of hospitalization at varying burden levels. The results will be used to develop more precisely targeted treatments to enable families and mentally ill persons to cope more effectively with the burdens of bipolar illness.